The Sun Rocks!
 

I have been thinking about building a solar block heater for my truck

Trying to start a brainstorming session here about creating such a beast, not the benifits of one.

I'm a bit skeptical about the big picture gains from using 750-1500 watts for two hours or however long it takes to heat up the engine on days I would drive, versus driving a cold engine for about 10 minutes. It may be cheaper but I don’t see the need to do the math. However I do value a warm engine especially on a cold day, This will only work when the sun is up but I think it will be effective



I’m thinking flat black alum tube heat collector in a 1 in thick paint sealed styro sheet, recessed plexi cover smooth beveled edges. Mounted on the passenger side of the hood. The panel itself will be 18in x12 in. I will have to drill two holes in the hood, which doesn’t bother me it has a few dents, scratches and creases, holes wont hurt.
I would like to avoid adding a circulation system, would the natural convection be effective? Will it even flow with the inlet and outlet at the same height? The inlet and outlet on the engine will be different heights maybe that’s enough?
Guess it doesn’t matter if I do need powered circulation I could drive it with a 12v solar panel.

Need some plumbing opinions should it be fixed loop flow, ie: always connected no block off or diverter valves. Or would such control of it be useful?
Should I try to Tee it with the heater core inlet outlet at the water pump, or run it in series after the heater core into the engine?


Dont know when I'll get started on the building of this, But I am sure I'll be able to accomplish something here pretty soon.

For a themosyphon to work, the hot part has to be at the bottom. Can you use flexible tubing and set the panel on the ground? Another approach would be to put reflective blanket insulation on the hood, and open it to the sun, with clear plastic to make the engine bay into a solar oven. Having a belly pan will help reduce losses from breezes in either case.

OK, a solar heater would only work during the daytime, so I'm assuming that you're not expecting this to have the engine warm first thing in the morning. So, how about just picking up a junkyard hood, painting it flat black, and having a "winter" and a "summer" hood?

Cut a hole in the hood, insulate the engine bay (belly pan, etc.) and put plexi in the hole. Park in the sun.

Thermosyphon probably won't do much for you here... it takes a long time for the effect to become... well, effective. Something as simple as a fish tank pump or even smaller would be sufficient. A condenser from an old A/C system would make a nice heat exchanger, or even the tube thing from the back of a fridge. Either could be mounted "cleanly" to the hood, and covered with a thin skin that would only cause minor aero problems, and be uncovered when necessary with a few screws or whatever.

If you really wanted to get fancy, you could cut a hole in the hood the same size as the heat exchanger, then fashion a bucket-thing for it to sit flush in, and mount it that way, using a flat cover when you're driving.

If you park near the dryer vent of your house, and your underhood area is insulated well enough, you could duct the dryer vent under your hood when your wife or you are doing laundry.

Not saying no to a solar project...

but a block heater only needs to be on an hour, even in severe cold. So that is what- 8 cents? Even if you didn't plan it out and you only plug it in for 1/2 hour, it still does something worthwhile.

It has been proven to be worthwhile too.

Maybe I should have done the math.

Guess I'll be focusing solar projects on the nonmobile things.

I've read about a number of people who berried a coiled of pex below the frost line, fitted it with a pump and some quick connect hydraulic hose fittings then fill it with anti freeze, then fit the vehicle with matching quick connect fittings on either side of the engine so you can pump 55 degree fluid in to your engine from the ground.
If I had a solar hot water system on my house I would add a block heater hook up to it like the ground source one I just described.
people have built systems with the quick connect fittings that use a propane burner as well, for heating up large equipment where electricity is not located.

With those quick connect thingies - would there be a problem with air pockets getting trapped in there every time they were (dis)connected?

Look fór some cheap mirrors and place them on the other side of the car. This will get sunshine on both sides of the engine bay, and double on the hood. If you had alot of big mirrors you might want to make a parabolic setup, focused on the engine. When the sun comes out, you'd better start running!

No, they are designed for hydraulic hoses on tractors and other equipment and in those systems air bubbles are a big problem, they also have a valve on both halves so you shouldn't have more then a few drops of fluid leak out.